Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs.

OBJECTIVE

To evaluate endotracheal tube intracuff pressure (P) changes over time and the effect of these changes on air leak pressure (P).

STUDY DESIGN

Prospective experimental study.

ANIMALS

A group of nine healthy adult Beagle dogs.

METHODS

In part I, in vitro measurements of P were recorded for 1 hour in eight endotracheal tubes subjected to four treatments: room temperature without lubricant (RT0L), room temperature with lubricant (RTWL), body temperature without lubricant (BT0L), and body temperature with lubricant (BTWL). In part II, nine dogs were endotracheally intubated and P was evaluated at P of 25 mmHg. Subsequently, P was reset to 25 mmHg (baseline) and P measurements were recorded every 5 minutes for 1 hour. Subsequently, a second P measurement was recorded at the current P. The data were analyzed using Wilcoxon signed-rank test, repeated measures anova and Mann-Whitney U test.

RESULTS

In part I, P differed significantly between the RT0L and RTWL treatments at 5-60 minutes, and between the BT0L and BTWL treatments at 5-35, 55 and 60 minutes (p < 0.05). In part II, compared with baseline pressures, mean P decreased to <18 mmHg at 10 minutes and significant decreases were recorded at 15-60 minutes (P range: 10.0 ± 4.9 to 13.4 ± 6.3 mmHg, mean ± standard deviation). Significant differences were observed between the first and second P measurements (p = 0.034). P decreased in six of nine dogs, was not changed in two dogs and increased in one dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Significant decreases in P over time were measured. P may decrease during anesthesia and increase the risk for silent pulmonary aspiration. The results indicate the need for testing P more than once, especially at 10 minutes after the onset of anesthesia.